Phosphenes
by bravevulnerability
Summary: "That was amazing. The way you kissed me." An AU moment for 3x13, 'Knockdown'.


_phosphenes (greek):_

 _"seeing stars"_

* * *

The air around them is brisk, chilled, but his lips burn. The cold sears his lonely mouth, whispers over the place her lips had just left, still wet with the taste of her, and he's still so dazed, so awed by the fact that he kissed Kate Beckett, that he hardly even notices her taking down the guard who'd been responsible for the ruse in the first place.

And when she blows out of breath, still holding onto the gun she'd clocked the man in the head with, all he can focus on is the swollen quality to her lips.

"That was amazing," he breathes, can't help it, can hardly feel ashamed even when Beckett glances back to him over her shoulder with tentative horror in her eyes.

"What?" she asks, her voice low, raspy, and oh, he can't stop hearing the way she had _moaned_ when she'd sucked his upper lip into her mouth.

"The way you kissed me," he confesses, watching the full-blown panic bloom across her face. "You - you're just… wow."

Kate releases a disgruntled noise from the back of her throat and swipes a hand through her hair, shifts her gaze back to the knocked out guard on the concrete.

"That - your dumb idea. It was just a dumb idea, a ruse," she counters with, wiping at her mouth with the back of her hand. Like she can erase him, the proof that he was there.

And maybe it's just because he's feeling bold tonight, maybe he's still drunk on the aftertaste of her mouth, but it lights a fire in his chest born of indignation. They may have to go save the boys right now, but this isn't going to be something he sweeps under the rug, lets her forget.

She can't erase this.

* * *

"The way you knocked that guard out was cool too," he muses later that night and Kate's eyes cut back to him, dread twisting through her stomach, because she doesn't have to guess where this conversation is eventually headed.

They're two of the last people left on the scene – Ryan and Esposito at the hospital despite all their grumbles, the paramedics gone, only a few tech investigators left on site and they're all inside the building. Outside, in the parking lot where he had kissed her, she and Castle are all alone.

"Mm, I think you beating a sniper with your bare hands wins out here," she teases back as they walk to her cruiser.

Like an idiot, she had offered to drive him home. Like a masochist, he had said yes.

"I think no matter what, I've won regardless," Castle hums and she finally huffs, comes to a stop that has him strolling around to stand in front of her, just like he'd probably wanted.

"I know what you're trying to do and I want you to stop," she demands, leveling him with her best detective glare, the one that has even the toughest of men on the opposite side of an interrogation table usually shrinking beneath her gaze in defeat. But Rick Castle knows her tricks, studies them all with diligence, and he simply tucks his hands into his coat pockets, wholly unfazed.

He shrugs, presents her with an innocent expression that she wants to wipe clean with the slap of her hand. Or maybe the punishing press of her mouth, the nip of her teeth. "Not sure what you're talking about."

"Okay fine, we kissed," she snaps, watching his eyebrows hitch, but he seems intrigued by her small outburst, eager to see where it leads. "It meant nothing. End of story."

Castle hums, but purses his lips. "I suppose that's a decent summarized version of what happened."

"Nothing else happened, Castle," she mutters, crossing her arms over her chest, not wavering even as he steps closer.

"Though, I don't agree with the last part."

"You said it yourself, dumb idea," she reminds him.

"True, but I think it meant something. Just like I meant it when I said it was amazing," he murmurs and her heart kicks up, accelerates, but she forces her composure to hold, for her expression to remain completely neutral. "You kissed me back."

"I had to," she shrugs, noticing the barely discernible flicker of hurt her words instill within the depths of his eyes, darkening from blue to a shuddering indigo.

"You arched into me, had your hands in my hair, your tongue in my mouth-"

"There was no tongue," she argues, but… well, there had been a little tongue.

"You moaned. Was that something you _had_ to do too?"

"I was playing it up."

"He wasn't close enough to _hear_ you," Rick counters and she wants to clock him with her gun too, knock some sense into him.

This isn't who they are, what they do. They don't _talk_ about these sorts of things and she thought he knew that, respected it. And maybe it wasn't fair, this one sided rule, but she'd consider rescinding it later. For tonight, for _this,_ the no talking policy remains strictly in place, and Kate strides past him before he can continue to defy it.

"Fine," he mutters, following her towards the car, and the tightness in her chest finally eases. "Pretend it meant nothing."

And just like that, it snaps.

"Why do you think I'm pretending?" she hisses, turning sharply on her heel, nearly causing him to run right into her. "Why does it have to mean something? Why the hell do you want it to?"

" _Why_?" he growls, incredulous, and god, she's just opened Pandora's box, hasn't she? But Castle shakes his head and brushes past her for the passenger side. "Doesn't matter, does it?"

"Castle-"

"You know, actually, thanks for the offer, but I'll just catch a cab back to my place. You should head home to your boyfriend," he sneers and she can't even pinpoint which part of this conversation is infuriating her the most, only that she's torn between wanting to kill him and kiss him again.

Josh has never made her feel this way, has never made her so conflicted in her want that she feels on the verge of exploding; Josh never elicits much passion to begin with.

This man, this idiot, had been damn near willing to beat a sniper to death for her, had acquired a batch of bruised knuckles for her, and she hated him for it. She hated the way her heart picked up speed for him more often than not, how it had exalted when he'd kissed her a mere two hours ago, the heat from their mouths spreading like flames through her system and sparking through her synapses. She still felt like she was on fire.

She wants it to mean nothing. She wants so badly for it not to mean anything.

But fire had spread through her veins and light had burst behind her eyes when he'd kissed her, tasting an explosion of stars on his lips and feeling the night air spark with heat around them and... it had been amazing.

"Castle, stop," she grumbles, pursuing him through the darkness and snatching him by the wrist.

He hisses and jerks his hand away from her, pulls it to his chest, and she falters, realizing she'd grabbed his bad hand, his pulsing knuckles.

"I'm sorry," she gets out, her voice sounding far and distant to her own ears, cracking, and her heart hollows out as the exhaustion so quickly claims his face, has him scrubbing his good hand over his eyes.

"I am too. You were right from the start. Let's just - just forget," he decides with a nod, resigned, and how did they become so complicated – more complicated than they already were prior to this night – so fast? "I'll see you tomorrow, Kate."

He saved her life and the dump of adrenaline through her veins is still pumping, and it's all wrong, it's shameful of her, but-

"Wait," she rasps, using the slight shift of his body to her advantage, planting her hands to his broad chest and pressing him back against the side of her car, her body sealing against his with the effort.

Castle stares down at her, bewildered and slightly concerned, but she's trapping his face between her hands before she can think better of it, before she can tell herself to stop.

Beckett arches into him, the same way she had earlier, and kisses him hard, bruises his mouth with hers, and doesn't even try to hold back the moan when he hauls her up against his body this time. His thigh slides between hers so easily, fits the jigsaw pieces of their hips into place, and Kate gasps, buries her fingers in his hair when his tongue slips inside. He'd held back in front of the guard, letting her lead, but he takes control now, trails his hands beneath her coat and glides his palms up her sides, strokes his thumbs to the undersides of her breasts.

Her spine bows into him and one of her legs instinctively hitches at his thigh, curls until the spike of her heel is stabbing into his calf and he's groaning a mixture of pleasure and pain into her mouth. His hands are beneath her shirt, fingertips scaling her spine and mapping the skin of her lower back, skating up to the clasp of her bra but never touching the thin material.

"Kate," he murmurs her name against the skin of her jaw, traveling down to the taut muscles of her neck that quiver and strain beneath his mouth, and she rocks her hips, pelvises colliding roughly, and oh god, not nothing. Good, _so_ good.

Her head drops back, into the cradle of his palm at her nape, allowing him to devour her throat, suck from the point of her pulse and sip from the hollowed pools her collarbones provide when he nudges her turtleneck out of the way.

She wants to reach past him to open the door to the passenger seat, shove him into the car and settle into his lap, undo his belt and ride the waves of heat that already threaten to drown her just from this moment alone.

Kate catches his head between her hands, tugs him back to her mouth and bites down on his bottom lip, arousal searing hot through her stomach at the growl he releases right before he curls his hand behind the knee at his thigh, jerks it to his hips and has her choking out a gasp, twisting her fingers tight in his hair.

"Gotta - gotta stop, Castle," she mumbles, but her own words fail to stop her fingers from clutching weakly at his coat collar, sliding beneath when the temptation to feel his bare skin on her fingertips calls to her, to scorch her hands against the heat of his flesh. "Fuck, make me stop."

He shudders out a breath, scalding and flushed against her lips, and gentles the intensity of his mouth's work, his kisses tender, whispering over hers and dusting the corner of her mouth, scaling the slash of her cheek, the edge of her brow.

"I never want to stop doing that," he husks, his grip on her knee easing, slowly guiding her leg down, her heel descending to touch the concrete once more. "I can't - not after this."

Her arms remain around him, holding her upright through their loop around his neck, and Kate sighs, uneven and shaky as she tries to catch her breath.

"I know," she confesses, her eyes fluttering shut with the reality of it, of what she's done to them both.

There's no coming back from this.

The brush of his mouth over hers has her sinking into the cove of his body, letting him lace his arms around her, hold her up as she braces her hands against the muscles of his biceps flexing beneath her palms.

This kiss is different, softer, more seductive, and she sighs, accepts the glide of his tongue inside her mouth with the welcoming stroke of her own. Sweeter, richer, but still devouring her, leaving her limp and useless in his arms with a pathetic mewl building in her throat. Her heart is pumping too hard while her lungs strain for oxygen and just as she thinks she's about to whimper into his mouth, Castle is drawing back from her lips, the sharp pant of his breathing matching her own.

"I'd never make you do anything you didn't want to do-"

"You didn't," she mumbles, far too throaty, but Rick simply combs the hair back from her face.

"So fair warning, Beckett. I intend to kiss you again. Whenever I can," he tells her like it's a promise. "And if you - want me as much as I want you-" After what they just did against the side of her car, is there really any question in that? "Then that won't be a problem anymore. Like it is now."

He's… oh, he's talking about her boyfriend. She has a boyfriend. Shit.

Kate swallows hard and forces her legs to hold as she straightens from the damn near boneless position against him, standing tall once more and allowing her hands to slip down to rest atop his chest.

"I'll - I'll make it right," she murmurs, because he deserves better, Josh deserves better, and though she rarely believes it, so does she. "Just… give me a little time?"

"How much time?"

"A few days." He sighs and Kate risks a glance to his face, sees the pout claiming his lips and huffs. "Impatient?"

"Duh. I regret how this happened, but I'm not… I can't be sorry," he admits and she nods her understanding, but she is. She's sorry for a lot of things.

She steps free from the warmth of his touch, gravitates away from him and towards the driver's side of Crown Vic, watching him slide into his usual seat from the corner of her eye while she starts the engine.

* * *

He kisses her goodnight because he knows she won't stop him, that she's obviously proven she doesn't want him to stop, but not on the lips. Castle lays a gentle kiss to her forehead, nothing more than a tender touch of his mouth to her skin, and Kate closes her eyes, lets herself have this innocent moment between them.

"Until tomorrow?" he asks, genuine uncertainty coloring his voice as he pulls away, and her eyes flutter open.

His lips are still subtly swollen, his eyes still alight with lust and longing that is usually well-hidden, and everything feels so different, so raw, but also the same. Like it's how it should be, how it was always going to be, because she had known from the moment he laid claim to her lips in that parking lot that it was never going to be the same again, that this outcome was ultimately inevitable.

"Tomorrow," she confirms.


End file.
